Objective:
The long-term objective of this project is to improve integrated pest management (IPM) practices for cereal aphids in wheat, sorghum, and barley in the United States. Achieving this objective will result in tools and knowledge to enhance the role of host plant resistance and natural enemies in IPM programs for cereal aphids, and fundamental knowledge of cereal aphid biology and ecology required for more effective crop management. Over the next 5 years we will focus on the following objectives:
Objective 1: Determine the genetic and biochemical basis for biotype formation in the Russian wheat aphid and greenbug by identifying salivary proteins, genes, and quantitative trait loci associated with virulence.
Subobjective 1A. Produce a systematic revision of greenbug, Schizaphis graminum (Rondani) sensu lato (i.e., in the wide sense), based on molecular methods.
Subobjective 1B. Map virulence and avirulence loci to wheat resistance genes in the Schizaphis graminum genome.
Subobjective 1C. Identify and characterize the salivary proteins injected during feeding by the Russian wheat aphid.
Subobjective 1D. Identify physiological and biochemical attributes that confer plant resistance to cereal aphids.
Objective 2: Monitor and characterize the biotypic structure of cereal aphid populations in the United States, and develop methods to efficiently determine their biotypic status.
Subobjective 2A. Determine the biotypic diversity in Russian wheat aphid populations at a regional level.
Subobjective 2B. Characterize holocyclic reproduction in the Russian wheat aphid and its role in biotype evolution.
Subobjective 2C. Characterize the role of non-cultivated grass species on the biotypic composition of greenbug populations and their occurrence, along with other cereal aphids, in small grain cropping systems.
Objective 3: Assess the effectiveness of key biological control agents in traditional and emerging small grain crop production systems and elucidate the intra- and extra-field processes that influence their population dynamics.
Subobjective 3A. Elucidate the effect of landscape factors on the population dynamics of the key greenbug parasitoid, Lysephlebus testaceipes.
Subobjective 3B. Elucidate the effect of co-occurring cereal aphids on parasitism of greenbug by Lysephlebus testaceipes.
Subobjective 3C. Assess the effect of non-cultivated hosts and wide-spread plantings of switchgrass (Panicum virgatum) on the biology, ecology, and tritrophic relationships of Hymenopterous parasitoids of cereal aphids.
Objective 4: Expand the existing Greenbug Decision Support System to include Russian wheat aphid IPM decision support.

Approach:
Field and laboratory experiments will be conducted to: (1) produce a systematic revision of greenbug based on molecular methods; (2) map virulence and avirulence loci to wheat resistance genes in the greenbug genome; (3) identify and characterize the salivary proteins injected during feeding by the Russian wheat aphid; (4) identify physiological and biochemical attributes that confer plant resistance to cereal aphids; (5) determine the biotypic diversity in Russian wheat aphid populations at a regional level; (6) characterize holocyclic reproduction in the Russian wheat aphid and its role in biotype evolution; (7) characterize the role of non-cultivated grass species on the biotypic composition of greenbug populations and their occurrence, along with other cereal aphids, in small grain cropping systems; (8) elucidate the effect of landscape factors on the population dynamics of the key greenbug parasitoid, Lysephlebus testaceipes; (9) elucidate the effect of co-occurring cereal aphids on parasitism of greenbug by L. testaceipes; (10) assess the effect on non-cultivated hosts and wide-spread plantings of switchgrass on the biology, ecology, and tritrophic relationships of Hymenopterous parasitoids of cereal aphids; and (11) develop sophisticated decision support computer software for greenbug and Russian wheat aphid pest management decision support that is comprehensive in scope yet easy for end users to understand and operate.